1. Field of the Invention
The present invention relates to a tofu (soybean curd) puree that can be applied to various food products and is useful in expanding the uses of soy milk, and to a method and apparatus for manufacturing this tofu puree. More particularly, the present invention relates to a tofu puree having the physical and chemical properties of (a) the viscosity is 20 to 3000 mPa.multidot.s, (b) the dynamic storage modulus is 0.2 to 600 Pa, (c) the dynamic loss modulus is 0.2 to 250 Pa, and (d) the particles contained in the tofu puree have an average size of 2 to 15 .mu.g m and a 90% particle size of 35 .mu.m or less (hereinafter (a) to (d) will sometimes be collectively referred to as "the specified physical and chemical properties), and that has no graininess, a superior texture, and good taste, and to a method and apparatus for manufacturing this tofu puree.
In this Specification, all percentages (%) are by weight unless otherwise specified, with the exception of particle distributions.
In this Specification, "Average particle size" refers to the particle diameter corresponding to 50% in the cumulative particle distribution, and the "90% particle size" refers to the particle diameter corresponding to 90% in the cumulative particle distribution.
2. Description of the Prior Art
In the past, as a method for manufacturing a tofu paste, a technique in which tofu with a water content of 87% is directly made into a paste with a silent cutter or the like has been disclosed (Japanese Laid-Open Patent Publication 6-46784; hereinafter referred to as Prior Art 1).
And a technic which comprises adding a coagulant to soy milk, allowing this mixture to stand for about 30 minutes at 80.degree. C. to coagulate the soy milk, pressing this product to lower the water content to between 70 and 80%, and then making this into a paste with a high-speed cutter or the like has also been disclosed (Japanese Laid-Open Patent Publication 2-86747; hereinafter referred to as Prior Art 2). Further, a technic which comprises adding a coagulant to 80.degree. C. soy milk and making a paste with a homogenizer has also been disclosed (Japanese Laid-Open Patent Publication 59-71641; hereinafter referred to as Prior Art 3).
Unfortunately, the following problems were encountered with this prior art.
A conventional tofu paste is produced, as mentioned above, from the tofu with or without being subjected to a water removal treatment, that is, after completely coagulating the soy milk, and therefore, as will be clear from the test examples given below, the viscosity thereof exceeds 3000 mPa.multidot.s, the dynamic storage modulus exceeds 600 Pa, the dynamic loss modulus exceeds 250 Pa, the average particle size exceeds 15 .mu.m, and the 90% particle size exceeds 35 .mu.m, and therefore, there has been the problem that the product has graininess and has a poor texture.
The paste produced by adding a coagulant to 80.degree. C. soy milk and homogenizing the mixture with a homogenizer is known, as above, but because this paste is produced with a homogenizer alone, as will be clear from the test examples given below, the average particle size exceeds 15 .mu.m and the 90% particle size exceeds 35 .mu.m, so the problems of graininess and poor texture thereof are encountered.
A tofu paste similar to a tofu puree was known in the past, as mentioned above, but a tofu puree, having the physical and chemical properties of (a) the viscosity is 20 to 3000 mPa.multidot.s, (b) the dynamic storage modulus is 0.2 to 600 Pa, (c) the dynamic loss modulus is 0.2 to 250 Pa, and (d) the particles contained in the tofu puree have an average size of 2 to 15 .mu.m and a 90% size of 35 .mu.m or less, and having no graininess, a superior texture, and a good taste, was not known.
In light of the above situation with prior art, the inventors have accomplished the present invention upon discovering that it is possible to manufacture a tofu puree whose viscosity, dynamic storage modulus, dynamic loss modulus, and size of the particles contained in the tofu puree meet specific numerical requirements, and which has no graininess, a superior texture, and a good taste, and therefore has many outstanding qualities unavailable in the past, by using an apparatus for manufacturing a tofu puree comprising a system in which a raw material tank, heating means, a holding pipe, first emulsifying dispersion means, cooling means, and second emulsifying dispersion means are arranged in that order, and coagulant supply means for supplying a coagulant, which is linked to this system between the heating means and the holding pipe, and by using the process comprises adding a coagulant to soy milk, holding the temperature at 40 to 90.degree. C. to coagulate the mixture, pre-crushing this coagulated product by first emulsifying dispersion means, cooling it to between 10.degree. C. and 35.degree. C., and crushing this pre-crushed product by second emulsifying dispersion means to particles having an average particle size of 2 to 15 .mu.m and a 90% particle size of 35 .mu.m or less.